1. FIELD OF THE INVENTION
The present invention is directed to commutators for use in two speed motors. In particular, a single commutator is provided on the rotor shaft to accommodate a multiple speed motor, particularly a two speed motor, utilizing minimal axial motor space.
2. DESCRIPTION OF RELATED ART
Dual winding type two speed electric motors are well known and require two commutators within the motor to direct electrical energy to the armature windings of the motor. One commutator is structured and wired to accommodate a first speed arrangement for the motor and the second commutator is structured and wired to accommodate the second speed of the motor.
Such systems encounter increased costs to develop, tool, inventory and process multiple commutators. In addition, the brush card complexity is increased because the brushes must operate on different planes within the motor. Furthermore, the axial space required to support multiple commutators generally increases the size of the motor.
Commonly assigned U.S. Pat. No. 4,910,790 relates to a two speed motor which utilizes a first radially extending commutator to accommodate one speed of the motor and a second cylindrical commutator to accommodate a second speed of the motor. The cylindrical commutator is mounted on the shaft of the motor and utilizes shaft space to accommodate the second speed commutator. The disclosure of U.S. Pat. No. 4,910,790 is incorporated herein by reference.
Commonly assigned U.S. Pat. No. 5,434,463 relates to a representative direct current motor which utilizes a commutator in combination with crescent shaped brushes. The disclosure of. U.S. Pat. No. 5,434,463 is incorporated herein by reference.
U.S. Pat. No, 5,095,611 relates to a method of assembling an electric motor to eliminate a separate end play adjustment wherein permanent magnets act on the armature laminations to urge the motor shaft in one direction so that the entire end play appears at only one end of the shaft. The disclosure of U.S. Pat. No. 5,095,611 is incorporated herein by reference.
Commonly assigned, concurrently filed U.S. patent application entitled Combined Armature and Structurally Supportive Commutator for Electric Motors, the disclosure of which is incorporated herein by reference, is directed to a novel combined armature and structurally supportive commutator wherein the rotational torque is transmitted to the armature by the commutator. Commonly assigned, concurrently filed U.S. patent application entitled Commutators for Electric Motors and Method of Manufacturing Same, the disclosure which is incorporated herein by reference, is directed to a novel method for manufacturing commutators for electric motors which eliminates costly manufacturing steps and loss of material.
U.S. Pat. No. 4,481,439 relates to a molded commutator made up of segments arranged in a ring with their brush contact surfaces facing inwardly and forming a cylindrical shape. A matrix of plastic is molded between and around the outside of the segment ring in order to separate the segments electrically and to hold them in the ring configuration.
U.S. Pat. No. 4,663,834 relates to a method for making an inverted commutator assembly for mounting on a rotor shaft, comprising forming a plurality of rotatable commutator segments with each segment having a brush contact surface into a ring in which the segments are circumferencially arranged in a spaced-apart relationship about a longitudinal axis of rotation, and placing reinforcing means in the form of an outer casing of high tensile strength material around the longitudinal axis of rotation for reinforcing the segments, molding a matrix of insulating material between the inside of the casing and the outside of the ring of segments and between the segments for electrically isolating the segments, and attaching to the matrix, means for affixing the commutator assembly to a rotatable shaft passing through the longitudinal axis of rotation.
U.S. Pat. No. 4,349,759 relates to a commutator for electrical machines and a method of manufacture of the commutator in which the commutator consists of a lamination assembly held together by a pair of shrink-rings. One of the rings serves to support the commutator on a commutator hub and comprises first and second ring portions having between them a decoupling portion. The first ring portion is in the form of a shrink-ring and holds together the lamination assembly. The second ring portion is secured to the commutator hub. The other shrink-ring also holds together the lamination assembly. In the method of manufacture of the commutator, both the first and second ring portions are simultaneously shrunk on to the lamination assembly and commutator hub respectively.
In engine compartments of modern day automobiles the need to minimize the space taken by the motor and related support equipment has become increasingly critical to the performance of the automobile. In particular, the need to reduce the axial length of the cooling motors has become increasingly significant. The present invention is directed to a unitary commutator which is capable of accommodating a two speed motor and which is structured and arrayed to minimize the space taken by the commutator within the motor along the axial length.